CN115832321B - Current collector, electrode plate, electrode assembly, battery and electric equipment - Google Patents
Current collector, electrode plate, electrode assembly, battery and electric equipment Download PDFInfo
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- CN115832321B CN115832321B CN202211400775.9A CN202211400775A CN115832321B CN 115832321 B CN115832321 B CN 115832321B CN 202211400775 A CN202211400775 A CN 202211400775A CN 115832321 B CN115832321 B CN 115832321B
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Abstract
The invention provides a current collector, an electrode pole piece, an electrode assembly, a battery and electric equipment, wherein the current collector comprises a supporting layer, a first surface and a second surface are formed on two sides of the supporting layer along the thickness direction, at least one of the first surface and the second surface is provided with a first area and a second area, and the second area is close to the edge side of the supporting layer; a conductive layer covering the first region; the insulating strips are arranged in the second area at intervals along the width direction of the plane where the supporting layer is located, and extend along the length direction of the supporting layer. Therefore, after the current collector is wound to form a battery, the success rate of cell metal spraying can be improved, the internal short circuit resistance of the pole piece is improved, and the safety of the battery is improved.
Description
Technical Field
The application relates to the technical field of batteries, in particular to a current collector, an electrode plate, an electrode assembly, a battery and electric equipment.
Background
With popularization and promotion of new energy automobiles, charge and discharge performance, cruising ability and the like of the new energy automobiles are increasingly attracting attention and importance. The power battery is a chargeable battery, is a power source of the new energy automobile and is widely applied in the field of the new energy automobile. In order to meet the structural requirement, the traditional composite current collector can be divided into a coating area and a welding area along the width direction, wherein the coating area is used for bearing an active material layer and collecting current generated by electrochemical reaction of active materials, and the welding area is used for connecting multiple layers of pole pieces together and connecting the pole pieces with a top cover in a welding mode to finish the connection of the pole pieces and battery poles. The multilayer pole pieces are connected in an ultrasonic welding mode, abrasion is easily generated in the junction area of the welding area and the coating area due to the speed difference between equipment and the current collector, and the scratch conducting layer is also easily damaged or even cracked, so that the sheet resistance of the pole pieces is increased and even the conductivity of the pole pieces is lost, and the internal short circuit resistance and the overcurrent resistance of the pole pieces are poor.
Thus, there is still a need for further improvements in current collectors.
Disclosure of Invention
The present invention aims to solve at least one of the technical problems in the related art to some extent.
In one aspect of the present invention, there is provided a current collector including a support layer having first and second surfaces formed on both sides thereof in a thickness direction, at least one of the first and second surfaces having first and second regions, the second region being adjacent to an edge side of the support layer; a conductive layer covering the first region; the insulating strips are arranged in the second area at intervals along the width direction of the plane where the supporting layer is located, and extend along the length direction of the supporting layer. Therefore, after the current collector is wound, the success rate of cell metal spraying can be improved, the internal short circuit resistance of the pole piece is improved, and the safety of the battery is improved.
According to some embodiments of the invention, the second region has a dimension L1 along the length of the support layer, the insulating strip has a dimension L2 along the length of the support layer, and 0.5mm L2L 1 is satisfied.
According to some embodiments of the invention, the dimension L1 of the second region satisfies: l1 is less than or equal to 1mm less than or equal to 5mm.
According to some embodiments of the invention, the insulating strip is formed of a non-conductive material including at least one of alumina, polyvinylidene fluoride, boron carbide, silicon carbide, boron nitride, silicon nitride, boron phosphide, silicon phosphide.
In another aspect of the present invention, an electrode sheet is provided, including the aforementioned current collector and an active layer, where the active layer is disposed on a side of the conductive layer facing away from the supporting layer and covers the conductive layer. Therefore, the electrode plate has all the characteristics and advantages of the current collector, and the description is omitted herein. In general, when it is made into a battery, it has at least the advantages of high energy density and high safety.
According to some embodiments of the invention, the conductive layer has a thickness D1, the insulating strip has a thickness D2, the active layer has a thickness D3, and: D2/(D1+D3) is less than or equal to 1.01 and less than or equal to 1.05.
According to some embodiments of the invention, 300 nm.ltoreq.D1.ltoreq.2μm; and/or 10 μm or less d3 is less than or equal to 200 mu m.
According to some embodiments of the invention, the electrode pad further comprises a metal deposition layer, wherein the metal deposition layer covers the end face of the electrode pad along the length direction of the supporting layer.
According to some embodiments of the invention, the metal deposition layer has a thickness D4 and satisfies: d is more than or equal to 0.5mm 4 mm or less.
According to some embodiments of the invention, an end of the conductive layer remote from the insulating strip is flush with an end of the active layer remote from the insulating strip.
According to some embodiments of the invention, the material forming the metal deposition layer comprises a metal conductive material.
According to some embodiments of the invention, the metallic conductive material comprises at least one of aluminum, copper, nickel, titanium, silver, nickel-copper alloy, aluminum-zirconium alloy.
In yet another aspect of the present invention, an electrode assembly is presented comprising a first electrode sheet and a second electrode sheet configured as the aforementioned electrode sheet; and the insulating piece is arranged between the first pole piece and the second pole piece. Therefore, the electrode assembly has all the characteristics and advantages of the electrode plate, which are not described herein, and generally has at least the advantages of better internal short circuit resistance and overcurrent capability.
According to some embodiments of the invention, the insulating strips on the first pole piece and the second pole piece are located at the same end of the insulating piece in the width direction of the supporting layer.
In yet another aspect of the present invention, a battery is provided that includes the aforementioned electrode assembly and an electrolyte. Thus, the battery has all the features and advantages of the electrode assembly, which are not described herein, and generally has at least the advantages of better internal short circuit resistance and overcurrent capability and higher safety.
In yet another aspect of the present invention, a powered device is provided that includes the aforementioned battery. Therefore, the electric equipment has all the characteristics and advantages of the battery, and the details are not repeated here. In general, the power supply device has the advantages of good power supply continuity and higher safety.
Drawings
The foregoing and/or additional aspects and advantages of the invention will become apparent and may be better understood from the following description of embodiments taken in conjunction with the accompanying drawings in which:
FIG. 1 is a schematic view showing a part of the structure of a current collector according to an embodiment of the present invention;
fig. 2 is a schematic view showing a structure of a current collector according to another embodiment of the present invention;
FIG. 3 shows a schematic view of the structure of an electrode sheet according to an embodiment of the present invention;
fig. 4 is a schematic view showing the structure of an electrode assembly according to an embodiment of the present invention;
fig. 5 is a schematic view showing the structure of an electrode assembly according to another embodiment of the present invention;
Fig. 6 shows a schematic structural view of a battery according to an embodiment of the present invention.
Reference numerals:
10: a current collector; 11: a support layer; a: a first region; b: a second region; 12: a conductive layer; 13: an insulating strip; 20: electrode pole pieces; 21: an active layer; 22: a metal deposition layer; 30: an electrode assembly; 31: a positive electrode sheet; 32: a negative electrode plate; 33: an insulating member; 40: and a battery.
Detailed Description
Embodiments of the present invention are described in detail below. The following examples are illustrative only and are not to be construed as limiting the invention. The examples are not to be construed as limiting the specific techniques or conditions described in the literature in this field or as per the specifications of the product. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
In one aspect of the present invention, a current collector 10 is provided, referring to fig. 1 and 2, the current collector 10 includes a support layer 11, a conductive layer 12, and a plurality of insulating strips 13, the support layer 11 is formed with a first surface and a second surface on both sides in a thickness direction, at least one of the first surface and the second surface has a first region a and a second region B near an edge side of the support layer 11, the conductive layer 12 covers the first region a, the plurality of insulating strips 13 are disposed in the second region B at intervals in a width direction of a plane in which the support layer 11 is located, and the insulating strips 13 extend in a length direction of the support layer 11. Specifically, the first surface and the second surface of the support layer 11 each have a first area a and a second area B, which are described in detail: the conductive layer 12 covers the first surface and the first area a on the second surface of the supporting layer 11, and insulating strips 13 are arranged at intervals in the second areas B on both sides of the supporting layer 11. Therefore, the pole piece formed by the current collector 10 has good internal short circuit resistance, high metal spraying success rate and higher safety of the formed battery 40.
The principle of the present application capable of achieving the above advantageous effects will be described in detail as follows:
The multilayer current collector 10 of the related art is often connected by welding, and the principle is to melt the multilayer metal at high temperature by using the energy of high-frequency ultrasonic waves and then cool and condense the multilayer metal together. Compared with the conventional metal current collector, the thickness of the metal conductive layer of the composite current collector is greatly reduced, and a great challenge is brought to welding: ultrasonic energy is too low, and metal layers cannot be effectively fused to generate virtual welding; the ultrasonic energy is too large, so that the metal layer is easy to be vibrated and cracked, and the flow conductivity is also influenced. Meanwhile, after the composite current collector is subjected to a coating process, the welding area is always exposed and is directly contacted with a driving roller system of equipment, abrasion and scratch are easily generated in the junction area between the welding area and the coating area due to the speed difference between the equipment and the current collector, and a submicron conductive layer is also easily damaged or even cracked, so that the sheet resistance of the pole piece is increased and even the conductivity is lost. The pole pieces which are subjected to the virtual welding and damage are removed in the working procedure of the battery cell manufacturing process, so that the manufacturing process rate is reduced and the manufacturing cost is increased; if the conductive layer which is in the false welding or damage is not identified in the production process, the conductive layer is easy to be further corroded by electrolyte after entering the battery core to cause failure, so that the cycle performance is seriously attenuated, and the reliability problem occurs. And after transfer welding, the height of the folded tab of the pole piece of the composite current collector is increased by about 7mm in an intangible way, so that the space utilization rate of the battery cell is greatly reduced. According to the current collector 10 provided by the application, the insulating strips 13 are arranged at intervals in the second area B of the current collector 10, so that when the current collector 10 is electrically connected with the battery pole through the metal deposition layer, metal particles can be prevented from falling on the adjacent other current collector 10 in the metal spraying process, the success rate of metal spraying of the battery core is further improved, the internal short circuit resistance of the pole piece is improved, and the safety of the battery is improved.
According to some embodiments of the present invention, the material forming the support layer 11 is not particularly limited, and may be, for example, at least one selected from an organic polymer insulating material, an inorganic insulating material, and a composite material. Wherein the composite material comprises an organic polymer insulating material and an inorganic insulating material.
According to some embodiments of the application, the organic polymer insulating material is selected from at least one of polyamide, polyterephthalate, polyimide, polyethylene, polypropylene, polystyrene, polyvinyl chloride, acrylonitrile-butadiene-styrene copolymer, polybutylene terephthalate, poly-paraphenylene terephthalamide, epoxy resin, polypropylene, polyoxymethylene, phenolic resin, polytetrafluoroethylene, silicone rubber, polyvinylidene fluoride, polycarbonate; the inorganic insulating material is at least one of alumina, silicon carbide and silicon dioxide; the composite material is at least one selected from epoxy resin glass fiber reinforced composite material and polyester resin glass fiber reinforced composite material. Therefore, since the density of the supporting layer 11 is generally smaller than that of metal, the current collector 10 provided by the application can improve the processability and the manufacturability of the current collector 10, improve the safety performance of the battery and improve the weight energy density of the battery. And the supporting layer 11 can perform good bearing and protecting functions on the conductive layer 12 positioned on the surface of the supporting layer, so that the pole piece breakage phenomenon common in the traditional current collector 10 is not easy to occur.
According to some embodiments of the present application, the thickness of the support layer 11 is not particularly limited, and a person skilled in the art may design according to the actual circumstances. In particular, the thickness of the support layer 11 may be 1 μm to 20 μm, specifically, 3 μm, 5 μm, 7 μm, 9 μm, 11 μm, 13 μm, 15 μm, 17 μm, etc. for the present application. Thereby, the supporting function of the conductive layer 12 and the insulating strip 13 can be satisfied. If the support layer 11 is too thin, the risk of breakage increases during the pole piece processing; if the supporting layer 11 is too thick, it occupies a space inside the battery, and the volumetric energy density of the battery formed by the current collector 10 is reduced to some extent.
According to some embodiments of the present invention, the material forming the conductive layer 12 is not particularly limited, and may be, for example, at least one selected from a metal conductive material and a carbon-based conductive material. The metal conductive material can be at least one selected from aluminum, copper, nickel, titanium, silver, nickel-copper alloy and aluminum-zirconium alloy, and the carbon-based conductive material can be at least one selected from graphite, acetylene black, graphene and carbon nanotubes.
Further, the process of forming the conductive layer 12 on the supporting layer 11 may be at least one of vapor deposition or electroless plating. Further, the vapor deposition method can be a physical vapor deposition method; still further, the physical vapor deposition method may be at least one of evaporation method and sputtering method; still further, the evaporation method is preferably at least one of vacuum evaporation method, thermal evaporation method and electron beam evaporation method, and the sputtering method is preferably a magnetron sputtering method.
According to some embodiments of the invention, the material forming the insulating strip 13 is a non-conductive material. Specifically, a film formed of a nonconductive material may be directly adhered to the supporting layer 11 to form the insulating bar 13; or the non-conductive material comprises an inorganic material and a binder, the inorganic material and the binder are mixed to form a slurry, and the slurry is coated on the surface of the supporting layer 11 to form the insulating strips 13. Specifically, the non-conductive material may include at least one of alumina, polyvinylidene fluoride, boron carbide, silicon carbide, boron nitride, silicon nitride, boron phosphide, and silicon phosphide. Thus, the insulation protection function is better.
According to some embodiments of the present invention, after the insulating strips 13 are disposed at intervals in the width direction of the supporting layer 11, exposed areas of the supporting layer are formed on the supporting layer 11 where the insulating strips 13 are not disposed, i.e., the exposed areas of the supporting layer are also disposed at intervals. Specifically, the barrier or the grease material can be removed to form the supporting layer exposing areas which are arranged at intervals after the preparation is finished by arranging the barrier or coating some grease material so that metal cannot be deposited in the area.
According to some embodiments of the present invention, referring to FIGS. 1 and 2, the second region B has a dimension L1 along the length of the support layer 11, the insulating strip 13 has a dimension L2 along the length of the support layer 11, and 0.5mm L2L 1 is satisfied. Thus, by controlling the length of the insulating strip 13, the volumetric energy density of the battery is improved on the basis of ensuring that the insulating strip 13 is not easy to break to perform the function of insulating protection.
Specifically, the size L1 of the second region B satisfies: 1 mm.ltoreq.L1.ltoreq.5mm, further, L1 may be 2mm, 3mm, 4mm or the like. Thereby, it is possible to reserve a sufficient space on the supporting layer 11 to provide the insulating strips 13 while not making the width of the current collector 10 as a whole too wide, affecting the volumetric energy density of the battery.
In another aspect of the present invention, an electrode tab 20 is provided, and referring to fig. 3, the electrode tab 20 includes the aforementioned current collector 10 and an active layer 21, the active layer 21 being disposed on a side of the conductive layer 12 facing away from the support layer 11 and covering the conductive layer 12. Thus, the electrode tab 20 has all of the features and advantages of the current collector 10 described above, and will not be described in detail herein. In general, when it is made into a battery, it has at least the advantages of high energy density and high safety.
According to some embodiments of the invention, referring to fig. 3, the thickness of the conductive layer 12 is D1, the thickness of the insulating strip 13 is D2, the thickness of the active layer 21 is D3, and the following are satisfied: D2/(D1+D3) is less than or equal to 1.01 and less than or equal to 1.05. Therefore, by controlling the thickness of the insulating strip 13 relative to the conductive layer 12 and the active layer 21, in the process of electrically connecting the electrode plate 20 and the battery post, the insulating strip 13 plays a better role in protecting the conductive layer 12 and the active layer 21, and meanwhile, the electrode plate 20 is prevented from occupying too large space in the thickness direction of the electrode plate 20, and the volume energy density of the battery 40 is prevented from being influenced.
Specifically, the thickness D1 of the conductive layer 12 may satisfy: 300 nm.ltoreq.D1.ltoreq.2μm, for example, D1 may be 500nm, 700nm, 900nm, 1.1 μm, 1.3 μm, 1.5 μm, 1.7 μm, 1.9 μm, etc.; and/or 10 μm.ltoreq.D3.ltoreq.200 μm, for example, D3 may be 30 μm,50 μm, 70 μm, 90 μm, 110 μm, 130 μm, 150 μm, 170 μm, 190 μm, etc. Therefore, the conductive layer 12 mainly plays a role of conducting and collecting current, and the thickness of the conductive layer 12 and the thickness of the active layer 21 are controlled, so that the overall conducting and collecting current performance of the electrode plate 20 is further controlled.
According to some embodiments of the invention, referring to fig. 3, the end of the conductive layer 12 remote from the insulating strip 13 is flush with the end of the active layer 21 remote from the insulating strip 13. Therefore, the active layer 21 completely covers the surface of the conductive layer 12, and a tab cutting area is not reserved on the conductive layer 12, so that a pole piece with an electrodeless tab structure can be formed, the space occupied by a battery core is saved, and the volume energy density of the battery is improved to a certain extent.
According to some embodiments of the present invention, referring to fig. 4 and 5, the electrode sheet 20 may further include a metal deposition layer 22, and the metal deposition layer 22 covers an end surface of the electrode sheet 20 along a length direction of the support layer 11. Therefore, the electrode plates 20 can be electrically connected with the poles of the battery 40 through the metal deposition layer 22, so that the overcurrent area of the electrode plates 20 is enlarged, the defect that the traditional lug is electrically connected with the poles after being folded is overcome, the occupied space of the folded lug of the battery core is saved, the volume of the battery core is reduced, the volume energy density of the battery 40 is improved, meanwhile, the internal resistance of the battery core is reduced, and the overall safety of the battery 40 is improved.
According to some embodiments of the present invention, referring to fig. 4, the thickness of the metal deposition layer 22 is D4, and satisfies: d4 is 0.5mm or less and 3mm or less, and further, the thickness of the metal deposition layer 22 may be 1mm to 2mm. Thus, the electrode tab 20 can be electrically connected to the battery post while avoiding an excessive thickness of the metal deposition layer 22, which increases the overall thickness of the tab.
According to some embodiments of the present application, the material forming the metal deposition layer 22 includes a metal conductive material. Further, the metallic conductive material includes at least one of aluminum, copper, nickel, titanium, silver, nickel-copper alloy, aluminum-zirconium alloy. Thereby, the electrode tab 20 is better electrically connected to the battery post. The metal spraying mode of the metallized film capacitor is to perform metal spraying treatment on one end of the pole piece to form a metal deposition layer 22, and after energization, welding two pins onto the metal deposition layer 22 of the battery core to lead out the pins. In the related art, zinc or zinc-tin alloy with low melting point is mostly used as a metal spraying material of the capacitor, and in a lithium ion battery, the zinc or zinc-tin alloy can be oxidized under high potential, if a similar metal spraying process of the capacitor is adopted, oxidation corrosion of the metal deposition layer 22 can be caused in the charging and discharging processes, and the connection effect is lost. And metals such as aluminum, copper, nickel and the like which are stable in the lithium ion battery are directly adopted, and the insulation part is heated and contracted due to the fact that the melting point of the metals is too high, so that the positive and negative plates are short-circuited. In order to better achieve the metal spraying welding effect, the metal conductive material forming the metal deposition layer 22 is preferably at least one of aluminum, copper, nickel, titanium, silver, nickel-copper alloy and aluminum-zirconium alloy, a thin metal deposition layer 22 is sprayed firstly by adopting a multiple metal spraying process, the end face of the battery cell is treated by a liquid nitrogen air knife before metal spraying, the surface needing metal spraying is rapidly cooled, and the heat generated in the metal spraying process can be well counteracted, so that the influence of excessive heat on an insulating part is prevented.
In still another aspect of the present invention, an electrode assembly 30 is provided that includes a first electrode sheet, a second electrode sheet configured as the aforementioned electrode sheet 20, and an insulating member 33 disposed between the first and second electrode sheets. For example, the first electrode sheet may be a positive electrode sheet 31, the second electrode sheet may be a negative electrode sheet 32, and the insulator 33 is disposed between the positive electrode sheet 31 and the negative electrode sheet 32. Thus, the electrode assembly 30 has all the features and advantages of the electrode sheet 20 described above, and will not be described herein. In general, the anti-internal short circuit device has at least the advantage of better anti-internal short circuit performance and better overcurrent capability.
According to some embodiments of the present invention, referring to fig. 4 and 5, the insulating strips 13 on the first and second pole pieces are located at the same end of the insulating member 33 in the width direction of the supporting layer 11. Therefore, the insulating strips 13 arranged on the first pole piece and the second pole piece at intervals can enable metal particles of the metal deposition layer 22 to fall on the insulating strips 13 in the process of spraying the metal deposition layer 22, so that the influence on the adjacent electrode pole pieces 20 is prevented, and the problem of internal short circuit is avoided.
In yet another aspect of the present invention, a battery 40 is provided that includes the aforementioned electrode assembly 30 and an electrolyte. Thus, the battery 40 has all the features and advantages of the electrode assembly 30 described above, and will not be described herein. In general, the anti-internal short circuit device has the advantages of better internal short circuit resistance, better overcurrent capability and higher safety.
According to some embodiments of the invention, referring to fig. 6, the length of the insulating strip 13 is M1, the length of the battery 40 is M, and the following is satisfied: M1/M is more than 0.5 and less than or equal to 0.6. Therefore, by controlling the ratio range of the coating length of the insulating strip 13 to the length of the battery cell, the success rate of metal spraying of the battery cell after final winding can be greatly increased, the phenomenon that metal spraying metal falls into the adjacent electrode pole piece 20 to cause short circuit inside the battery cell is avoided, and the reliability of electrodeless lug welding and the safety performance of the battery cell are further improved.
In yet another aspect of the present invention, a powered device is provided that includes the aforementioned battery 40. Thus, the powered device has all the features and advantages of the foregoing battery 40, and are not described in detail herein. In general, the power supply device has the advantages of good power supply continuity and higher safety.
1. Preparation of current collector
And placing the support layer subjected to surface cleaning treatment in a vacuum plating chamber, melting and evaporating high-purity metal wires in a metal evaporation chamber at a high temperature of 1600-2000 ℃, and finally depositing the evaporated metal on the surface of the support layer through a cooling system in the vacuum plating chamber to form a conductive layer. The melting mechanism of the metal wire consists of a plurality of melting units (comprising an evaporation boat, a wire feeding mechanism and a heating current loop) which are arranged along the width direction of the substrate and are independently controlled. Wherein by adding baffles or oiling, a second area with fixed width and not evaporated is left to act as a supporting layer when the insulating strip material is coated in the MD direction.
The thickness test method of the supporting layer/conducting layer comprises the following steps: the liquid nitrogen quenching method or the argon ion etching method is used for preparing a sample with a cross section of the current collector, a scanning electron microscope is used for amplifying (1000-5000 times) the secondary electron phase morphology of the cross section of the sample, the thickness of the conducting layer and the thickness of the supporting layer are measured, and the minimum resolution can reach the nanometer level.
The second area width measuring method comprises the following steps: the width test was performed using a graduated scale.
2. Preparation of the cell
And coating positive electrode slurry or negative electrode slurry on the surface of the current collector through a special intermittent battery coating process. The insulating strip is coated on the end face of the pole piece at the length of M1, the length of the battery cell is M, and the ratio Y=M1/M is more than or equal to 0.5 and less than or equal to 0.6. And (3) drying at 100 ℃ to obtain a positive electrode plate or a negative electrode plate with a special structure, and fully coating active substances on a first area of the electrode plate to form the electrode plate with the electrodeless ear structure. And compacting the surface active substances of the positive electrode plate and the negative electrode plate through a conventional battery cold pressing process, wherein the compaction of the positive electrode plate is set to be 2.5-4.5g/cm 3, and the compaction of the negative electrode plate is set to be 1.0-2.0g/cm 3.
And then winding the positive electrode plate, the diaphragm and the negative electrode plate together into a bare cell through a conventional battery manufacturing process.
3. Performance testing
① To evaluate the reliability of the metal-sprayed welding, the bonding force of the metal deposition layer was evaluated.
The testing method comprises the following steps: the binding force of the metal deposition layer was measured using a high-iron tensile machine. And (5) carrying out a peeling force test on the semi-finished product dry cell subjected to metal spraying through a 90-degree peeling method. And (3) sticking yellow adhesive with stronger adhesive force on the metal deposition layer, stripping the sample at a speed of 5mm/min, and reading the average value of stripping force.
The evaluation method comprises the following steps: and selecting 32 samples for testing, and evaluating the mechanical combination effect of spray welding by using the average value and standard deviation of the welding stripping force of the samples, wherein the calculation formulas of the average value and the standard deviation of the welding stripping force are as follows:
Welding peel force average = 32 sample welding peel force value sum/32
Standard deviation of weld peel force= [ sum of weld peel force values-average of weld peel force of each sample/32 ] 1/2.
② Withstand voltage test (Hi-post test): hi-Pot test results of 500 cells were collected.
Cell Hi-post bad product rate = Hi-post bad product cell count/500 x 100%.
Finally, the lithium ion secondary battery is put into a battery shell, electrolyte is injected (the volume ratio of ethylene carbonate to methyl ethyl carbonate is 3:7, and LiPF 6 is 1 mol/L), and then the procedures of sealing, formation and the like are carried out, so that the lithium ion secondary battery is finally obtained.
③ The DCR values of 500 cells were collected.
④ And collecting temperature rise data of 10 electric cores to evaluate the effect.
Metal deposition layer thickness screening
The differences in the thickness of the metal deposition layers in the batteries of each example and comparative example are shown in Table 1, and the results of the performance tests of each example and comparative example are shown in Table 2:
TABLE 1
TABLE 2
As can be seen from Table 2, when the thickness of the metal deposition layer is 0.2mm, the stripping force of the metal spraying position is 33N/m, the stripping force cannot meet the practical use requirement, the cold joint is easily caused in the process of welding with the top cover in the later stage, DCR is increased, and the temperature rise of the position is increased, so that the cell fails. When the metal spraying thickness is larger than 3mm, the cooling effect of the liquid nitrogen air knife cannot offset the heat of the metal spraying amount, the diaphragm can be possibly deformed, and the metal spraying particles fall into the electrode slice to cause the Hi-post poor proportion to be increased to about 50%. As can be seen from Table 2, when the thickness of the metal deposition layer is between 0.5mm and 3.0mm, the stripping force of the metal spraying position can meet the use requirement, and the cooling effect of the liquid nitrogen air knife in the metal spraying process is good, so that the temperature rise is not excessively large. When the thickness of the metal deposition layer is 1mm-2.0mm, the metal spraying efficiency can be further improved, and the welding reliability is ensured.
Insulation strip thickness screening
The thicknesses of the insulating strips in the examples and comparative examples are shown in Table 3, and the effects of the thicknesses of the insulating strips in the examples and comparative examples on Hi-Pot failure rates are shown in Table 4:
TABLE 3 Table 3
TABLE 4 Table 4
As can be seen from table 4, the thickness of the insulating strip in comparative example 3 is smaller than the sum of the thickness of the active layer and the thickness of the conductive layer, and at this time, metal particles are sprayed onto the adjacent pole pieces in the metal spraying process, so that the Hi-post defective rate is improved; when the thickness of the insulating strip/(the thickness of the active layer+the thickness of the conductive layer) in the embodiment 3, the embodiment 5 and the embodiment 6 is 1.01-1.05, metal particles can be prevented from being sprayed onto adjacent pole pieces in the metal spraying process, if the thickness of the insulating strip is too thick, the problem of edge rolling and edge bulging can be easily caused in the cold pressing stage of the previous working procedure, and therefore, the thickness of the insulating strip is preferably just capable of covering the end face to be protected.
Insulation strip coating length screening
The lengths of the electrode plate insulating strips in the examples and the comparative examples are shown in Table 5, and the influence of the intermittent coating of the insulating strips on the yield of the battery cells is shown in Table 6:
TABLE 5
TABLE 6
| Sequence number | Hi-post bad quality rate (500 cells) |
| Example 8 | 100％OK |
| Example 9 | 100％OK |
| Example 10 | 100％OK |
| Comparative example 4 | 77％OK |
As can be seen from table 6, when the intermittent coating length of the insulating strip is smaller, the adjacent pole pieces cannot be well protected in the process of metal spraying welding, and metal spraying particles can splash to the middle position of the top end of the battery cell, so that the internal short circuit of the battery cell is caused, and the Hi-post is bad.
In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present invention.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.
In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
In the present invention, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.
While embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the invention.
Claims (17)
1. A current collector, comprising:
A support layer having a first surface and a second surface formed on both sides thereof in a thickness direction, at least one of the first surface and the second surface having a first region and a second region, the second region being adjacent to an edge side of the support layer;
a conductive layer covering the first region;
The insulating strips are arranged in the second area at intervals along the width direction of the plane where the supporting layer is located, and extend along the length direction of the supporting layer.
2. The current collector of claim 1, wherein the second region has a dimension L1 along the length of the support layer, the insulating strip has a dimension L2 along the length of the support layer, and 0.5mm L2L 1 is satisfied.
3. The current collector of claim 2, wherein the dimension L1 of the second region satisfies: l1 is less than or equal to 1mm less than or equal to 5mm.
4. The current collector of claim 1, wherein the material forming the insulating strip is a non-conductive material comprising at least one of alumina, polyvinylidene fluoride, boron carbide, silicon carbide, boron nitride, silicon nitride, boron phosphide, silicon phosphide.
5. An electrode sheet, comprising:
A current collector configured as the current collector of any one of claims 1 to 4;
the active layer is arranged on one side of the conductive layer, which is away from the supporting layer, and covers the conductive layer.
6. The electrode pad of claim 5, wherein the conductive layer has a thickness D1, the insulating strip has a thickness D2, the active layer has a thickness D3, and the following are satisfied: D2/(D1+D3) is less than or equal to 1.01 and less than or equal to 1.05.
7. The electrode sheet according to claim 6, wherein 300 nm.ltoreq.d1.ltoreq.2μm; and/or 10 μm or less d3 is less than or equal to 200 mu m.
8. The electrode pad of claim 5, further comprising a metal deposition layer covering an end face of the electrode pad along a length direction of the support layer.
9. The electrode pad of claim 8, wherein the metal deposition layer has a thickness D4 and satisfies: d is more than or equal to 0.5mm 4mm or less.
10. The electrode pad of claim 8, wherein an end of the conductive layer distal from the insulating strip is flush with an end of the active layer distal from the insulating strip.
11. The electrode pad of claim 8, wherein the material forming the metal deposition layer comprises a metal conductive material.
12. The electrode pad of claim 11, wherein the metallic conductive material comprises at least one of aluminum, copper, nickel, titanium, silver, nickel-copper alloy, aluminum-zirconium alloy.
13. An electrode assembly, comprising:
a first pole piece and a second pole piece configured as the electrode pole piece of any one of claims 5-12;
And the insulating piece is arranged between the first pole piece and the second pole piece.
14. The electrode assembly of claim 13, wherein insulating strips on the first and second electrode sheets are located at the same end of the insulating member in the width direction of the support layer.
15. A battery comprising the electrode assembly of any one of claims 13 and 14 and an electrolyte.
16. The battery of claim 15, wherein the insulating strip has a length M1, the battery has a length M, and the battery satisfies: M1/M is more than 0.5 and less than or equal to 0.6.
17. A powered device comprising the battery of any of claims 15 and 16.
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| CN111180666A (en) * | 2019-06-28 | 2020-05-19 | 宁德时代新能源科技股份有限公司 | Electrode plate and electrochemical device |
| CN114830402A (en) * | 2021-07-14 | 2022-07-29 | 宁德新能源科技有限公司 | Electrochemical device and electronic device |
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| CN114883633B (en) * | 2022-05-09 | 2024-07-16 | 江苏正力新能电池技术有限公司 | Electric core, battery module and battery package |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111180666A (en) * | 2019-06-28 | 2020-05-19 | 宁德时代新能源科技股份有限公司 | Electrode plate and electrochemical device |
| CN114830402A (en) * | 2021-07-14 | 2022-07-29 | 宁德新能源科技有限公司 | Electrochemical device and electronic device |
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